update error message

src/compiler/parse/state/tag.ts

@@ -250,7 +250,7 @@ function read_tag_name(parser: Parser) {
 		if (!legal) {
 			parser.error({
 				code: `invalid-self-placement`,
-				message: `<svelte:self> components can only exist inside if-blocks, each-blocks or within a component`
+				message: `<svelte:self> components can only exist inside {#if} blocks, {#each} blocks, or slots passed to components`
 			}, start);
 		}
 

test/parser/samples/error-self-reference/error.json

@@ -1,6 +1,6 @@
 {
 	"code": "invalid-self-placement",
-	"message": "<svelte:self> components can only exist inside if-blocks, each-blocks or within a component",
+	"message": "<svelte:self> components can only exist inside {#if} blocks, {#each} blocks, or slots passed to components",
 	"start": {
 		"line": 1,
 		"column": 1,